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What Caused the Dinosaur Extinction?

theatlantic.com

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Re: What Caused the Dinosaur Extinction?

#21

Post by pfdietz »

ian0 wrote: post #16
pfdietz wrote: post #4

The evidence for a massive impact precisely at the K/T boundary is ironclad. Any alternate theory in which the impact was not causal has to explain how this incredible coincidence (the largest impact in the past 100 million years occurring in a layer deposited in just thousands of years, right at the boundary) occurred.

This struck me as precisely the type of thing that they were giving out about in the article. So I asked a geologist was there more to it. They said: The Cretaceous-Paleocene event is dated to 66m years ago [1]. The crater has been dated to 65m years ago [2]. The deccan traps was from 63-69m years ago with the bulk of activity 66m years ago [3]. Obviously both the volcano and the meteor were life-changing events. Of…

There is no evidence the dinosaurs were on their way out. The evidence is entirely consistent with abrupt extinction with no precursor decline.

The global mass extinction killed things that can be much more precisely dated than dinosaurs. Forams, for example, go extinct right at the impact boundary, cut off like a knife.

Re: What Caused the Dinosaur Extinction?

#22

Post by mirimir »

ian0 wrote: post #16
pfdietz wrote: post #4

The evidence for a massive impact precisely at the K/T boundary is ironclad. Any alternate theory in which the impact was not causal has to explain how this incredible coincidence (the largest impact in the past 100 million years occurring in a layer deposited in just thousands of years, right at the boundary) occurred.

This struck me as precisely the type of thing that they were giving out about in the article. So I asked a geologist was there more to it. They said: The Cretaceous-Paleocene event is dated to 66m years ago [1]. The crater has been dated to 65m years ago [2]. The deccan traps was from 63-69m years ago with the bulk of activity 66m years ago [3]. Obviously both the volcano and the meteor were life-changing events. Of…

If that dating is at all accurate, it seems pretty obvious that both Deccan Traps and the Chicxulub impact contributed. I don't get why it's gotta be either-or.

Re: What Caused the Dinosaur Extinction?

#23

Post by listenYou »

vertline2 wrote: post #14
pfdietz wrote: post #4

The evidence for a massive impact precisely at the K/T boundary is ironclad. Any alternate theory in which the impact was not causal has to explain how this incredible coincidence (the largest impact in the past 100 million years occurring in a layer deposited in just thousands of years, right at the boundary) occurred.

Is it possible for a meteor to cause a chain of volcanoes to blow? like all the pressure under the crust gets rattled around?

I mean, this is definitely my goto theory. Everything tied up in one single package.

But, unfortunately, just because we like something, doesn't mean it really went down that way. And rightfully so, a horde of nerds will come out of the woodwork, to inform us if we were to claim the validity of an event, without true evidence in hand.

Either way, it won't stop me from harboring a deep suspicion that this is exactly what happened.

Mostly, my own belief is founded in similar conceptual origins for the moon.

Re: What Caused the Dinosaur Extinction?

#24

Post by samth »

pfdietz wrote: post #21
ian0 wrote: post #16

Earlier quoted context omitted.

This struck me as precisely the type of thing that they were giving out about in the article. So I asked a geologist was there more to it. They said: The Cretaceous-Paleocene event is dated to 66m years ago [1]. The crater has been dated to 65m years ago [2]. The deccan traps was from 63-69m years ago with the bulk of activity 66m years ago [3]. Obviously both the volcano and the meteor were life-changing events. Of…

There is no evidence the dinosaurs were on their way out. The evidence is entirely consistent with abrupt extinction with no precursor decline. The global mass extinction killed things that can be much more precisely dated than dinosaurs. Forams, for example, go extinct right at the impact boundary, cut off like a knife.

The article is, roughly, about a geologist who studies exactly forams and disagrees.

Re: What Caused the Dinosaur Extinction?

#25

Post by GlennS »

lkrubner wrote: post #10

Start with a 3 species model. Imagine a shallow, closed sea, in which there is a shark, a plesiosaur, and a bird. We need to explain why the shark and the bird survive, but the plesiosaur goes extinct. An asteroid hits somewhere, causing environmental change. For the rest of this comment, I'm going to refer to temperature as a short-hand way of referring to any environmental change. The shallow, closed sea is undergo…

I don't see how you would distinguish this from a guess?

Why prefer this over any other of the millions of possible explanations? Ecosystems are complicated.

Re: What Caused the Dinosaur Extinction?

#26

Post by nimchimpsky »

mirimir wrote: post #22
ian0 wrote: post #16

Earlier quoted context omitted.

This struck me as precisely the type of thing that they were giving out about in the article. So I asked a geologist was there more to it. They said: The Cretaceous-Paleocene event is dated to 66m years ago [1]. The crater has been dated to 65m years ago [2]. The deccan traps was from 63-69m years ago with the bulk of activity 66m years ago [3]. Obviously both the volcano and the meteor were life-changing events. Of…

If that dating is at all accurate, it seems pretty obvious that both Deccan Traps and the Chicxulub impact contributed. I don't get why it's gotta be either-or.

The impact caused the Deccan traps, like if you punch a jelly, stuff spurts out the opposite side.

Re: What Caused the Dinosaur Extinction?

#28

Post by ncmncm »

tl;dr: Stuff happened 65+ mya. Theories developed over past ~50 years. Human extinction due in 50 y to 0.5 my. Implication: there is no need to rush a conclusion. New evidence will continue to surface. We might be extinct before certainty arrives.

Re: What Caused the Dinosaur Extinction?

#29

Post by ridgeguy »

vertline2 wrote: post #14
pfdietz wrote: post #4

The evidence for a massive impact precisely at the K/T boundary is ironclad. Any alternate theory in which the impact was not causal has to explain how this incredible coincidence (the largest impact in the past 100 million years occurring in a layer deposited in just thousands of years, right at the boundary) occurred.

Is it possible for a meteor to cause a chain of volcanoes to blow? like all the pressure under the crust gets rattled around?

Maybe.

On Mercury, it seems the impact that created the Caloris basin [1] may also have created a seriously busted-up region at its antipode (opposite on the planet from the impact) [2]. This may have happened due to shock waves propagating through Mercury's interior, focused by reflection at the planet's surface onto an area opposite the impact. There are alternate theories.

A few years ago, I looked into whether the Deccan Traps eruptions might have been either triggered or enhanced by similar antipodal seismic wave energy from the Chicxulub impact. Based on Earth's continental positions about 65M years ago, it seemed possible, maybe plausible. There were some papers discussing the possibility, but I don't have the data at hand.

[1] https://en.wikipedia.org/wiki/Caloris_Planitia [2] https://en.wikipedia.org/wiki/Caloris_Planitia#Antipodal_cha...

Re: What Caused the Dinosaur Extinction?

#30

Post by BuckRogers »

Excellent article that I thoroughly enjoyed. I had no idea there was any other compelling explanation for the dinosaurs' extinction other than an asteroid but it makes sense. It's definitely convincing enough that it shouldn't be dismissed outright and it sounds like about half of the scientific community is doing just that.
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